The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time or filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Communication systems typically comprise transmitters that transmit data over a communication channel and receivers that receive data transmitted by transmitters. Often, receivers receive data that may be corrupted due to co-channel interference (CCI) and/or adjacent channel interference (ACI). CCI may be caused by a signal operating on the same channel that carries data. On the other hand, ACI may be caused by a signal operating in a channel that is adjacent to a channel carrying data.
Interference may distort data. That is, data received by receivers may not represent data transmitted by transmitters due to interference. Consequently, receivers may not accurately interpret and process received data resulting in partial or total data loss. This can degrade system performance and may cause system malfunction.
Referring now to FIGS. 1A-1B, a receiver 10 typically comprises an antenna 30, an automatic gain control (AGC) module 32, a mixer module 33, and a local oscillator module 33-1. The receiver 10 further comprises a filter module 34, an analog-to-digital converter (ADC) module 36, and a digital signal processor (DSP) module 38.
The antenna 30 receives an input signal. The AGC module 32 has a gain that varies based strength of the input signal. The mixer module 33 mixes a signal generated by the local oscillator module 33-1 with the input signal. The filter module 34 filters an output of the mixer module 33. The ADC module 36 converts an output of the filter module 34 from analog to digital format. The DSP module 38 processes an output of the ADC module 36.
Additionally, the receiver 10 typically comprises a peak detector module 40 that generates a peak-detect signal when the output of the AGC module 32 crosses a predetermined threshold in response to the input signal. The predetermined threshold is generally based on characteristics such as packet size, packet length, strength of the input signal, etc. The peak detector module 40 may generate the peak-detect signal when the AGC module 32 determines that the input signal strength exceeds a relative signal strength index (RSSI).
The peak-detect signal activates the DSP module 38. The DSP module 38 generates a gain-drop signal that drops the gain of the AGC module 32 as shown in FIG. 1B. The gain of the AGC module 32 remains low for the duration of the input signal. The duration of the input signal depends on characteristics such as packet size, packet length, etc. The gain of the AGC module 32 returns to normal at the end of the input signal.
On the other hand, an interference signal may trigger a false alarm. That is, the interference signal may cause the peak detector module 40 to mistake the interference signal as data. The peak detector module 40 may generate the peak-detect signal when the input signal is an interference signal. Subsequently, the DSP module 38 may generate the gain-drop signal that will drop the gain of the AGC module 32. The gain of the AGC module 32, however, may not return to normal since the interference signal may have unknown and/or unknowable characteristics. This can cause system malfunction and/or data loss.